Conventional incandescent lighting systems utilize dimming control circuits or dimmers to adjust the intensity or brightness of light provided by the system. A conventional dimmer works by adjusting the portion of an alternating current (AC) half wave that is supplied to the incandescent light being powered. Such an AC signal is a sinusoidal AC power signal and the “half wave” of the signal corresponds to this sinusoidal signal during half the period of the signal, as will be understood by those skilled in the art. The portion of the AC power signal that is actually supplied through the dimmer to an incandescent light or other load being powered is commonly referred to as the “conduction angle” of the AC power signal. To control the brightness of the light provided by the system the dimmer reduces the portion of each AC half wave that is supplied to the light and thereby controls the root-mean-square (RMS) voltage supplied to the light. The RMS voltage supplied to the light determines the brightness of the light being provided and in this way the dimmer controls the brightness.
In light emitting diode (LED) lighting systems, which are becoming popular replacements for conventional incandescent lighting systems, control circuitry operates to maintain a desired average current supplied to the LEDs being powered to thereby achieve the desired illumination. These control systems maintain the desired average current independent of variation in the supplied AC input voltage. As a result, conventional dimmers cannot be utilized with these LED control circuits since the control circuits will simply adjust the current supplied to the LEDs to maintain the desired average current in response to changes in the AC input voltage caused by the dimmer. It is, however, desirable to utilize conventional dimmers with such LED lighting systems to provide compatibility of LEDs with existing incandescent lighting systems.